It has long been possible to test both qualitatively and quantitatively for ionic materials in an aqueous sample by electrolytic means, and to record the electrical potential of deposition of the ions on an electrode. In one form of such testing known as stripping voltammetry, the ions are first deposited on an electrode and thereafter the potential is continuously or continually varied to strip the deposited material from the electrode and redissolve it in the sample liquid. This operation is known as stripping voltammetry and since it is ordinarily used by plating cathodically and stripping anodically to detect and measure metallic ions, it is often known as anodic stripping voltammetry. By means of anodic stripping voltammetry, it has been found possible to perform relatively quick simple and accurate tests to measure minute traces of appropriate materials. Recently, in connection with environmental studies, it has become important to collect small quantities of polluting impurities from the atmosphere or from other portions of the environment to test for the presence of dangerous pollutants. A very immediate concern has been the need to test for the presence of informative or dangerous impurities in the human bloodstream, and anodic stripping voltammetry has proven itself capable of performing such tests. The present inventor and his associates have been interested in problems relating to this general field of activity for a number of years. Among other things, they have devised and developed certain useful apparatus for anodic stripping voltammetry as disclosed in application Ser. No. 167,330 (now abandoned) and certain improved electrodes disclosed in Ser. No. 168,161 (now abandoned) and Ser. No. 327,788, now U.S. Pat. No. 3,855,099, granted Dec. 17, 1974. The present invention is a unified system for anodic stripping voltammetry or cathodic stripping voltammetry capable of performing analysis of trace materials on an extremely rapid and an extremely accurate basis. In particular, the system according to the present invention can analyze human blood samples in the field or in the normal environment of such human beings at the rate of many hundreds of samples per day and can obtain critical output data regarding the presence of impurities such as lead, cadmium, zinc or the like in the human bloodstream within about a minute after a blood sample is actually taken from the human being, thus permitting such sampling in the environment of the real world. The quickness of completion of testing is of unusual importance, in light of experience which shows that the 7% of people tested in urban slum areas cannot later be located if they are once allowed to leave the test area.